Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

194
FXUS63 KLOT 211801
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1201 PM CST Wed Jan 21 2026

.KEY MESSAGES...

- A strong Arctic front will bring a 1-2 hour period of gusty
  snow showers (greatest coverage north of I-80). Winds gusting
  to 40+ mph may lead to patchy blowing and drifting snow
  through tonight where snow falls.

- A second Arctic front will usher in an extended period of
  dangerous cold Thursday night through early next week.

- An Extreme Cold Watch has been issued for late Thursday night
  into Friday morning for areas near and north of Interstate-55
  where wind chills may drop below -30F.

&&

.DISCUSSION...
Issued at 340 AM CST Wed Jan 21 2026

After a burst of heavier snow across far northern Illinois and
even in parts of northwest Indiana, snow has mostly struggled to
fill in over much of the area early this morning. Still can`t
rule out the development of a secondary southerly band resulting
in an additional dusting near and east of Interstate-55, but
given impacts are not anticipated to be at the level of a Winter
Weather Advisory, have accordingly cancelled it early. Still
can`t rule out some slick spots into the first part of the AM
commute where roads are still partially snow covered and where
any additional snow falls through mid morning.

With less snow having fallen overnight, temperatures today are
anticipated to warm into the 30s near and south of I-88 (mid-
upper 20s north). In fact, some areas well south of I-80 could
touch 40 by this afternoon. Winds will become breezy out of the
west southeast by this afternoon with gusts to 20-25 mph.

Attention will quickly turn to this evening when a strong
Arctic front is expected to push across the area. This feature
in question is currently progressing across northern North
Dakota early this morning and is expected to race southeast
with time toward the area through the day. While confidence in a
short period of snow showers and gusty winds developing is high
for this period, there remains uncertainty with their
intensity. Steepening low-level lapse rates could support a
short 1-2 hour burst of snow (and quick accumulations to 1")
followed by a period of wind gusts to 40+ mph through the
evening. This could be paired with blowing and drifting snow
where snow does accumulate. Have elected to hold off on either
a Wind Advisory or Winter Weather Advisory issuance on this
shift and will let the day shift get one final look at things to
determine which product best fits the message based on upstream
trends (and if warranted).

Winds will ease gradually after midnight through daybreak
Thursday, remaining breezy. Forecast highs on Thursday are in
the 20s for most of the area with upper teens toward the
Wisconsin state line. A second Arctic front then pushes across
the area later in the day on Thursday. This could also be paired
with some gusty snow showers, albeit with less coverage than
this evening. Did introduce a formal mention of snow showers in
the forecast with this update to account for this.

Temperatures are expected to plummet in the wake of the front
Thursday night, potentially well below zero across interior
northern Illinois. Winds could still be in the 15-25 mph range
out of the northwest through the morning on Friday. Because of
this, wind chills will have the potential to drop below -30F for
portions of the area. Accordingly, have issue an Extreme Cold
Watch for areas generally near and north of Interstate-55. Can`t
rule out counties on the southeast periphery of the Watch being
converted to a Cold Weather Advisory instead of a Warning with
later updates if temperatures trend a bit warmer than currently
forecast, but the message for dangerous cold will remain
unchanged for early Friday morning! While not as extreme as
early Friday AM, wind chills may remain colder than -15F
through Saturday morning across the region. Be sure to check on
family members and neighbors regularly during this stretch of
very cold air. Bundle up in several layers if you must head
outdoors.

Lake effect snow may occur into parts of northwest Indiana in
the wake of Thursday`s front at times through Saturday.
Confidence in the details at this distance remain low, but
something to monitor for those in northern Porter County.

A major winter storm is expected to take shape to our south
late week. There remains some uncertainty with the handling of
a trailing wave diving out of Canada and how it interacts/phases
with the southern system. This could lead to accumulating snow
lifting as far north as the local area Saturday night into
Sunday (currently 30-40% chance). The EPS remains the most
consistent with this signal and will be something to monitor
closely over the coming days.

Petr

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1201 AM CST Wed Jan 21 2026

Forecast concerns for the terminals...

- Period of gusty snow showers this evening resulting in IFR
  visibilities.

- West-northwest winds tonight gusting around 30 kts with a
  period of higher gusts with the snow showers.


While many sites across northeast IL and northwest IN have
scattered out this morning, a plume of BKN MVFR ceilings is
slowly spreading east across northern IL. Given the broken
nature of the MVFR ceilings suspect they won`t persist at the
Chicago area terminals for more than 2-3 hours, but confidence
on when exactly the terminals will scatter out is low.
Otherwise, expect breezy westerly winds gusting 20-25 kts this
afternoon.

The arctic front currently moving across the Dakotas will move
into northern IL around 00z this evening. A band of gusty snow
showers will arrive with the front and result in a 2-3 hour
window of IFR visibilities and MVFR ceilings at the terminals.
Though, confidence is growing that locally lower visibilities
(as low as 1/4SM) may occur briefly with the snow showers
particularly for areas near the IL-WI line. In terms of
accumulation, the cold ground temperatures should result in at
least a half inch for many with some localized pockets of 1 to
maybe 2 inch amounts near the IL-WI line. Outside of the snow
showers, west-northwest winds will be gusting around 30 kts with
a period of higher gusts (35-40kts) expected with the snow
showers. That said, anywhere that sees at least 1 inch of
accumulation from the snow showers may also get some blowing and
drifting snow overnight with these winds.

Heading into Thursday, winds will gradually decrease Thursday
morning with 20-25 kt gusts expected through the rest of the
forecast period. Skies will also scatter back to VFR shortly
after the snow showers end with SCT to BKN skies expected
through Thursday afternoon.

Yack

&&

.MARINE...
Issued at 1106 PM CST Tue Jan 20 2026

Have issued a Gale Warning for all of our nearshore zones
Wednesday night. Another formidable arctic cold front is slated
to push through the region Wednesday evening, causing west-
southwesterly winds to turn westerly/west-northwesterly and gust
to at least 35 kts behind the front. Some potential for 40 kt
gales exists as well, though confidence in this is only low-
medium at this time. Gusts will gradually subside with time
Thursday morning as the front and associated low pressure center
progress eastward.

Some consideration may need to be given to a Heavy Freezing
Spray Warning for our nearshore zones adjacent to Porter County,
IN. However, at this time, it appears that the more significant
heavy freezing spray risk will remain over the open waters of
Lake Michigan.

Ogorek

&&

.HYDROLOGY...
Issued at 258 PM CST Mon Jan 19 2026

Area hydrographs and ice spotter reports confirm that ice
continues to develop and spread across areal rivers. Localized ice
jams are already present along the Rock, Des Plaines, and Fox
Rivers. Continued cold temperatures tonight and Tuesday will
cause ice to continue expanding and thickening.

After a brief warm-up in temperatures to above 20 degrees on
Tuesday-Wednesday, another push of bitterly cold temperatures
will arrive Thursday night. As a result, the threat for ice
jams including localized flooding will increase further toward
the end of the week and through the weekend.

- NWS Chicago

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Extreme Cold Watch from late Thursday night through Friday
     morning for ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
     ILZ011-ILZ012-ILZ013-ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-
     ILZ103-ILZ104-ILZ105-ILZ106-ILZ107-ILZ108.

IN...None.
LM...Small Craft Advisory until 7 PM CST this evening for the IL
     and IN nearshore waters.

     Gale Warning from 7 PM this evening to 6 AM CST Thursday for
     the IL and IN nearshore waters.

     Heavy Freezing Spray Warning from midnight tonight to 10 AM
     CST Thursday for Gary to Burns Harbor IN-Burns Harbor to
     Michigan City IN.

&&

$$

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